Did you know that you can check the accuracy of your speedo, using the digital trip computer functions on your Gallardo? This check shows that my speedo over-reads by 10%. (Australian Design Rules for all cars allows a maximum of 6% error in speedo reading, so strictly speaking Lamborghini have delivered me a car that is technically illegal in this country!).

The signals that drive the odometer and speedo are digital pulses that are taken from a sensor somewhere in the transmission. As long as they have done their sums right, and worked out the correct diff and gear ratios, then the pulse rate (or frequency) must be 100% correct. The only remaining variable is the diameter/circumference of the tyre. Let's assume for now that they have this correct.

This being the case, the pulse rate being sent to the odometer, speedo, and trip computer should be correct. If there was an error (say by tyre diameter), it would effect equally odometer, speedo and trip computer by the same percentage. This is how I came across the problem.

Try this. Set the trip computer to read average speed. Then drive at a constant speed, then press, hold and release the Reset button (under the stalk). The display will then immediately read the new "average" speed, and at the instant you let go the reset button, the average speed = the instantaneous speed. So you get an accurate digital read-out of your road speed at that point in time. Immediately look at your speedo reading. If it does not read the same, then there is an "error" in the digital reading compared with the analogue speedo reading. Not surprising really, considering the accuracy of an analogue speedo is based on 40's technology meter movements, ie hair spring tensions and magnet strengths. They need to be individually calibrated to give accurate readings. Seems this is not happening on the Gallardo.

Maybe just coincidence, but my wife's new Audi A3 shows exactly the same 10% over-reading speed error. Both gauges are made by VDO, for Audi/Lamborghini.

The problem has been reported by my dealer, back through the distributor to the factory, but no response so far.